1. Field of the Invention
The present invention relates to a light-emitting diode (LED) lamp, and more particularly, to an LED lamp in which LEDs are respectively mounted on top and bottom surfaces of a substrate so that light can be radiated not only in a forward direction but also in a rearward direction of the substrate, thereby obtaining a characteristic of light distribution similar to that of an incandescent lamp.
2. Discussion of the Background
Light-emitting diodes (LEDs) may be used as light sources in various fields because of characteristics such as high efficiency and definition. A conventional lamp may be replaced with an LED lamp, and LEDs may be applied in the illumination field.
The orientation angle of an LED lamp may be 120 degrees, which is the conventional orientation angle of an LED used as a light emitting source. Conventionally, when an LED has been used as a lamp, its light efficiency, lifetime, or the like has been considered, but a characteristic of its orientation angle has not been considered.
However, a demand for LED lamps having characteristics of orientation angle and light distribution similar to those of conventional incandescent lamps has recently increased.
Lens type, reflector type, and vertical type LED lamps have been developed so that their characteristics of orientation angle and light distribution are similar to those of the conventional incandescent lamps.
However, a reflector type LED lamp may radiate light to a rear portion of an LED that is a light emitting source, but have a relatively low light efficiency. A lens type LED lamp may be superior to the reflector type LED lamp in terms of light control and light efficiency, but may have a technical difficulty in implementing a characteristic of an orientation angle of light. Particularly, there it may be difficult to radiate light toward a rear portion of an LED.
Meanwhile, a vertical type LED lamp emits light in a sideward direction by disposing an upper portion of an LED in a vertical direction, thereby acting as a conventional lightbulb. Therefore, the vertical type LED lamp may have an excellent light distribution curve, but may have difficulty in controlling the LED to emit light uniformly in all directions. In addition, since it may be necessary to partition a substrate having the LED mounted thereon, it may be difficult to ensure operability of the LED, and also may increase manufacturing cost.